As an image forming apparatus using an electrophotographic method, there is known a printer which has photosensitive members for carrying developer images, and transfer members for transferring the developer images formed on the photosensitive members onto a sheet.
For example, there has been proposed a related-art color image forming apparatus which has photosensitive drums, a plurality of developing units that is arranged in parallel along peripheries of the photosensitive drums, and transfer rollers that are provided on the downstream sides of the plurality of developing units in the rotation directions of the photosensitive drums such that they face the photosensitive drums.
In this color image forming apparatus, pre-transfer lighting means (PTL) are provided between the plurality of developers and the transfer rollers. Then, before toner images formed on the photosensitive drums are transferred onto a sheet P, infrared beams are irradiated onto the photosensitive drums by the pre-transfer lighting means. In this way, the potentials of the surfaces of the photosensitive drums are generally lowered, whereby the potential difference between portions of the surfaces of the photosensitive drums having no toner attached thereto and portions of the surfaces of the photosensitive drums having toner attached thereto is reduced.